A sample of potassium has an average atomic mass of 39.0983amu. There are three isotopic forms of potassium element in the sample. About 93.2581% of the potassium atoms are 38.9637amu mass (39K); 0.0117% are 39.9639amu mass (40K), and the remaining isotope 41K is of 40.9618amu mass. Calculate the percentage composition of 41K. Report your answer with five significant figures.

Answer asap need by wednesday morning explain how a buffer works, using an ethanoic acid/sodium ethanoate system including how the system resists changes in ph upon addition of a small amount of base and upon addition of a small amount of acid respectively. include the following calculations in your i. calculate the ph of a solution made by mixing 25cm3 0.1m ch3cooh and 40cm3 0.1m ch3coo-na+. [ka = 1.74 x 10-5 m] ii. calculate the ph following the addition of a 10cm3 portion of 0.08 m naoh to 500cm3 of this buffer solution. iii. calculate the ph following the addition of a 10cm3 portion of 0.08 m hcl to 200cm3 of the original buffer solution.